I. Field of the Invention
The present invention relates to ambulatory devices for physically handicapped individuals and, in particular, to an ambulatory wheelstand having multiple angular positions in which the center of gravity of the user remains centrally disposed above a particular location on the wheelstand frame. The wheelstand of the present invention includes torso and leg support.
II. Description of the Prior Art
Ambulatory device have been used to enable a non-ambulatory person, such as a paraplegic or a quadriplegic, to move about more or less on his own, Typical wheeelchairs were the first types of ambulatory devices, but required the user to remain in one position, thus causing atrophy of the muscles.
Wheelstands first resembled a cross between a wheelchair and a gurney and employed a foldable or pivotable stretcher portion which could pivot between a horizontal and an upright position. Examples of these earlier wheelstands can be found in U.S. Pat. Nos. 2,295,006 to Philips and 2,986,200 to Nobile. Each of these patents discloses a device having a large central driving wheel rotatably attached to a frame stabilized by castor wheels at the front and the rear of the device. The patient support is pivotably secured to the frame and includes either a straight stretcher or a somewhat chair-shaped platform to support the user. The support is pivotable between an upright position and a horizontal position. Because of the relatively high pivoting point of the support structure of these devices, the center of gravity of the devices is quite high, rendering the device somewhat unstable. The front and rear castor wheels are required to improve stability.
U.S. Pat. No. 4,310,167 to McLaurin discloses what the inventor calls a center of gravity wheelchair with an articulated chassis. This wheelchair also has a large drive wheel centrally located and both front and rear castor wheels. The chassis is articulated so that the user can shift the center of gravity of the device forward by operation of a lever which extends the chassis frame and the front castor wheel, thus elongating the frame and improving the stability. This device is particularly useful for negotiating curbs, hills or the like. However, McLaurin still employs front and rear castors and allows the user to assume a sitting position only.
Two improved ambulatory wheelstands are disclosed in U.S. Pat. Nos. 4,620,714 and 4,927,167, both to Davis. The '714 patent disclosed a wheelstand having a generally rectangular main frame supported on a ground support surface by two relatively large wheels disposed between a pair of relatively small rear wheels and a pair of relatively small front wheels. The '167 patent also discloses a wheelstand having a user support structure pivotably mounted on a frame.
While these early inventions all played a part in improving the conditions of non-ambulatory persons, they have failed to provide for the specific needs of certain afflicted individuals. The wheelstands that comprise the prior art have utility for many physically handicapped persons, but nevertheless fail to provide for the specific needs of certain afflicted individuals. More particularly, the known wheelstands provide only minimal support for individuals suffering from one of the various cerebral palsy syndromes. These individuals require special trunks and leg support. Even more specific needs are had by those persons grouped in the spastic syndrome. These individuals make up about seventy percent of cerebral palsy cases. The spastic patient requires special care because the affected limbs of the patient usually show increased deep tendon reflexes and muscular hypertonicity and a tendency to contractures. The muscles controlling the limbs tend to contract spontaneously, causing spastic torso and limb movements. None of the known wheelstands is capable of responding to these special needs.